Diabetes is a disease caused by an insulin deficiency or a resistance to insulin in the body. Type I diabetes is an autoimmune disease that damages the beta cells of the islets of Langerhans in the pancreas, resulting in an inadequate amount of insulin in the body. Without insulin treatments, Type I diabetes is fatal. Type II diabetes results from an insufficient production of insulin or an inability of the patient's body to respond properly to insulin. Insulin resistance associated with Type II diabetes prevents adequate levels of blood sugar from entering into cells to be stored for energy, resulting in hyperglycemia in the bloodstream. Traditionally, Type I diabetes is treated by repeated subcutaneous injections of insulin each day. Type II diabetes is also treated with insulin, often in combination with other medications taken orally or by injection. Multiple injections of insulin per day are required, as well as careful monitoring of the patient's blood glucose levels through dietary control and blood testing. Insulin pumps are used as an alternative to multiple daily insulin injections by a syringe. However, insulin pumps are costly, must be worn most of the time, and require blood testing to determine the amount of insulin to deliver into the patient. Blood testing requires the patient to draw a sample of blood, usually from a finger, and to test the blood sample for glucose concentration. Blood glucose monitoring systems are available that use a sensor placed just under the skin to periodically monitor the amount of glucose in the interstitial fluid. These systems require calibration, typically resulting in two finger pricks per day, and are costly. Moreover, a lag time exists between the concentration of glucose in the bloodstream and the concentration of glucose in the interstitial fluid.
A need exists for a system or device that delivers controlled amounts of insulin directly in response to increased glucose concentrations, without requiring the patient or medical professional to continuously monitor the blood glucose level, determine the appropriate amount of insulin to be injected, and inject the insulin periodically throughout the day.